Hi

While driving in the city everything works fine. But driving on highway the car began to steam like a old train. After driving coolant fluid is dripping on parking lot and coolant tank gets empty. Upper hose, radiator and thermostat has been already changed. What could be the problem? There is the motor heater installed in my car, so could that be location for the problem?

 

Jetidogi, odds are, your nipple for the return line to the overflow bottle is cracked and is leaking coolant out. I bet your coolant is dripping down behind the left front tire. If so, this is almost confirmation that this is what your problem is. In short, there is very little clearance near this nipple and if something gets in there, it can bend the nipple and crack it where it attaches to the tank.

 

^^yup, yup